Rapid growth of amount of data exchange brings a challenge to an electronic packet-switched network in terms of size, cost and energy consumption. The capacity of the network is eventually limited by potential bottlenecks in routers. Effective approaches to break the bottlenecks include introducing an all-optical switching technology.
However, existing optical circuit switching (OCS) can only exchange data at a wavelength granularity, leading to inefficient bandwidth utilization of the network. Optical packet switching (OPS) can exchange data at an ultrafine sub-wavelength granularity, but all-optical buffers and all-optical logic devices are required in OPS. Since all-optical buffers and all-optical logic devices are not mature and cannot be put into practice, the prospect of development in OPS is not promising in the foreseeable future. Optical burst switching (OBS) can be regarded as a combination of OCS and OPS while avoiding their shortcomings in a certain extent. Using out-of-band signaling, OBS can exchange data at a sub-wavelength granularity without all-optical buffers. However, like OPS, OBS cannot guarantee reliable data transmission due to packet loss. Even worse, without buffers the loss rate of packets at a heavy load could be much higher in OBS than that in conventional packet-switched networks, which limits the application of OBS.
Hence, in current all-optical switching networks, there are some defects in OCS, OPS and OBS and there is no all-optical switching technology for overcoming these defects.